@hillsab03: Here are the dimensions I used. Hope this helps anyone who wants to make one.

I used foam board for the actual letter which i drew on with just a pencil and ruler and cut out with an exacto knife. Then the sides of the letter are poster board which I cut in to strips 5 1/2 inches wide. I drew a line at 2 inches on each strip and that is where I taped it onto the foam letter. I didn’t use any glue just packaging tape used to attach it together on the back of each letter. The link I posted above helps a lot.